I needed a circle-cutting attachment for my Porter-Cable plunge router, so I decided to modify the existing guide. I removed the three flathead screws holding the edge guide shoe and set it aside. I then replaced the two outer screws for safekeeping and threaded a short length of 10 – 24 threaded rod into the center hole to act as pivot. In a few minutes (and at practically no cost), I had a circle-cutting attachment with micrometer adjustment.
– Ron Watkins